Process for obtaining fertilizers



Patented Sept. 20, 1932 STATES FRITZ RO'IHE AND HANS BRENEK, OF

RHENANIA-KUNHEIN VEREIN CHEMISCHEB FABRIKEN BERLIN, GERMANY BERLIN,GERMANY, ASSIGNORS TO THE FIRM AKTIENGESELLSCHAFT, OF

PROCESS FOR OBTAINING FERTILIZERS No Drawing. Original app1ication filedJune 28, 1927, Serial No. 202,156, and in Germany .Tune 28,

Divided and this application filed April 17, 1928. Serial No. 270,790.

The invention has reference to a process for obtaining fertilizers fromcrude phos phates with utilization of sodium chlorides. As sodiumchloride represents a relatively cheap sodium-compound, its utilizationrenders the process quite economical. Furthermore it is thereby possibleto obtain hydrochloric acid as by-product.

According to the invention a mixture containing crude phosphates, sodiumchloride and silica in such quantity that molecule of silica correspondsto one molecule of P 0 is subjected to a heating treatment, preferablyat a temperature of at least 900 C. in the presence of steam. At such atreatment the silica is thought to withdraw one molecule ofCaO from thecalciumphosphate so that in the case of tricalciumphos'phatealkalidicalciumphosphate on the one hand and calciumorthosilicate on theother hand are formed. v

It is of special importance that such lime present in the mixture whichis not bound to the phosphoric acid is converted intocalciumorthosilicate by silica. For this reason if the phosphorites tobe treated contain lime not bound to phosphoric acid originally forinstance in the form of calciumcarbonate or calciumfluoride, then it isnecessary to add further quantities of silica in excess of molecule forevery molecule of P 0 so that in every case two molecules of CaOcorrespond to one molecule of SiO In this respect it must be pointedout, however, that any amounts of iron or alumina which may be containedin the phosphorites used for this process can replace the silica and canform with CaO calciumaluminate orcalciumferrite. Any amounts of suchmaterials therefore must be considered on calculating the requiredcomposition of the mixture to be heated.

Preferred temperatures for the described process are between 900 and1200 centigrade.

The product obtained by the process herein described has a very highcontent of total phosphoric acid and also of citrate soluble phosphoricacid. It is a special advantage of this process, that the amount ofsilica added to the mixture is considerably lowered compared with formersimilar processes which made use of silica at the manufacture offertilizers from crude phosphates.

Example 100 parts of a containing 39.7% of P 0 47,0% of C20 bound to P 05,6% of Ca-O not bound to P 0 and 0.56% of Si0 are mixed with 11,5 partsof quartz and 33 parts of technical sodium chloride and heated at atemperature of about 1100 centigrade in the presence of steam. The totalamount of P 0 contained in the heating product are 31,99% and theproduct contains '31,28% of citrate soluble P 0 (soluble in a citratesolution according to Petermann) that is to say 97,8% of the totalamount of phosphoric acid have been rendered soluble. The heatingproduct contains still only 0.11% of Cl.

What we claim and desire to secure by Letters Patent of the UnitedStates is:

1. A process for obtaining fertilizers comprising heating a mixture ofphosphates with silica and sodiumchloride in the presence of steam,there being present for every molecule of P 0 in the mixture, an amountof silica substantially equal to and not exceeding half a molecule. v

2. A process for obtaining fertilizers comprising heating a mixture ofphosphates with silica and sodiumchloride in the presence of steam,there being present for every molecule of P 0 in the mixture an amountof silica substantially equal to and not exceeding half a molecule, carebeing taken for transforming the CaO not bound to phosphoric acid in aninsoluble form.

3. A process for obtaining fertilizers comprising heating a mixture ofphosphates with silica and sodiumchloride in the presence of steam to atemperature of at least 900 centigrade. there being present for everymolecule of P 0 in the mixture, an amount of silica substantially equalto and not exceeding half a molecule.

4:. A process for obtaining fertilizers comprising heating a mixture ofphosphates with silica and sodiumchloride in the presence of NorthAfrican phosphate,-

steam to a temperature between 900 and 1200 centigrade, there beingpresent for every molecule of P 0 in the mixture, an amount of silicasubstantially equal to and not exceeding half a molecule.

5. A process for obtaining fertilizers comprising heating a mixture ofphosphates with silica and sodlumchloride in the presence of steam to atemperature of at least 900 centigrade, there being present for everymolecule of P 0 in the mixture, an amount of silica substantially equalto and not exceeding half a molecule and care being taken for trans-'forming the Ca() not bound to phosphoric acid into an insoluble form. r

6. A process for obtaining fertilizers comprising heating a mixture ofphosphates with silica and sodiumchloride in the presence of steam,there being present an amount of silica substantially equal to and notexceeding one half a molecule for every molecule of P 0 andsubstantially one molecule of silica for two molecules of CaO.

. HANS BRENEK.

FRITZ ROTHE.

